Act I Scene 4 - Olivier '48

Visually, Hamlet is already teetering on the edge - of sanity - as we come into Scene 4. He's still rather calm and Horatio is at best matter-of-fact, as per their usual characterizations in this film. It continues the feeling set up in Scene 1 that the supernatural is a normal part of this world.

This time, we see the King's rouse, albeit from afar, down in the courtyard.
So we can trust Hamlet's take on events a lot more, and in any case, the party doesn't take on the feeling of a private orgy it does in Branagh's version. And Olivier doesn't play Hamlet's speech as a rant either, but more as a reflection. He isn't outraged, but perhaps more disappointed in his own countrymen's reputation. The pauses he takes makes it all seem like a new idea rather than an old point of contention. Branagh's Hamlet had rehearsed the speech a hundred times in his head (which certainly fits the idea of Hamlet as a Player), but Olivier's speaks/hears it for the first time (more in line with Bloom's "characters overhearing themselves" concept.

The Ghost's arrival is heralded by a sense of anxiety created by a pulsing heartbeat that makes the camera go in and out of focus on Hamlet.
Along with Hamlet's suicidal tendencies shown at the top of the scene through its staging, this camera trick helps create a point of view for the character. Is he in fact insane? He's certainly unstable, and Horatio will be right to fear that the Ghost will drawn him "into madness". One answer to the reality/unreality of the Ghost is that it is real (in this supernatural world), not a figment of Hamlet's madness, but responsible for it. He only needs a small push, and this apparition gives Hamlet one more ball to juggle in his already confused mind. However, while supernatural is accepted by the characters, we might still believe it to be the result of superstition. In that case, the Ghost's appearance is merely a by-product of their point of view, and the modern viewer could say it was due to a trick of the light and the fog. And when it speaks, it is Hamlet's madness that speaks (but then the end of Scene 5 might be problematic). Certainly, this image of the Ghost is indistinct enough to support that interpretation.
Hamlet pulls out his sword to "make a ghost that lets" him, but also uses it as a cross to protect himself from evil before taking off after the Ghost.
The last exchange between Horatio and Marcellus is cut from this version (just as a number of words are changed, "clep" to "call" is a particularly annoying example), again supporting Hamlet's point of view through this scene. He wouldn't have heard them. The effect on plot is minimal, though it does remove some well-known lines. This version of the film continues to marginalize these secondary characters in favor of Hamlet, which is a perfectly legitimate way of addressing the play's length.